1. Field of the Invention
This invention relates to a gear type power transmission, and more particularly to an element device for obtaining a gear type continuously variable transmission.
2. Description of the Prior Art
Although there has been known a little mechanical continuously variable transmission mechanism achieved by using gears, of these mechanisms a rectangular wave-generating apparatus disclosed in Japanese Patent Publication No. 59-42181 (1984) seems to be a typical one example of an element device of mechanical continuously variable transmission mechanisms according to the prior art. It is disclosed in the above described Japanese Patent Publication that a continuously variable transmission can be composed of a plurality of sets of such rectangular wave-generating devices. However, one set of element devices of the conventional example comprises four non-circular spur gears and three bevel gears, that is to say seven gears in all and is based on the construction consisting of at least ten mechanical elements. Accordingly, with a continuously variable transmission using the above described set of element devices, a difficulty of the conventional continuously variable transmission is that a large number of constituent mechanical elements including specialized gears, such as non-circular gears and bevel gears, are required.
In general, a friction gearing is superior in smoothness of the rotary transmission while a non-friction gearing, such as a gear, is superior in transmission efficiency. However, in comparison with friction gearing, a conventional continuously variable transmission non-friction gears has a difficulty in that the construction is remarkably complex. Therefore, the transmission efficiency is reduced by inertia loss due to the constituent mechanical elements and the friction between the mechanical elements.